Elastic ip addresses and cost

amazon-elastic-ipamazon-web-services

I always understood that you can have one ip for free, then you start paying for it. Also, it has to be associated.

But i need another one for my mailserver, and after reading their documentation word for word, i read it as, per instance.

Is that true? Can i have up to 5 elastic addresses for free as long as they are associated to my instances?

You can have one Elastic IP (EIP) address associated with a running instance at no charge. If you associate additional EIPs with that instance, you will be charged for each additional EIP associated with that instance per hour on a pro rata basis. Additional EIPs are only available in Amazon VPC.

Best Answer

Yes, you understood correctly. You are allowed 5 per region (can be increased if you need more, but you have to explain why). They don't cost anything as long as they are being used, e.g. by an EC2 instance or NAT gateway.

Related Solutions

AWS VPC Multiple IPs

Your /etc/network/interfaces file probably has something like the following:

auto eth0
iface eth0 inet static
    address 192.0.2.10
    netmask 255.255.255.0
    gateway 192.168.2.1

This is what assigns the primary IP (it may also be DHCP). To assign a secondary IP add a post-up script to attach an additional address to eth0.

auto eth0
iface eth0 inet static
    address 192.0.2.10
    netmask 255.255.255.0
    gateway 192.168.2.1
    up ip addr add 192.168.2.20/24 dev eth0

Elastic IP vs EC2 Public Hostname + Route53

Amazon will happily lift this limit for you. In my experience, this only takes a few hours to go through.
Correct, you should never use an EIP for internal EC2-to-EC2 traffic.
Not if you use VPC (which you absolutely should if you're ever going to use more than a single standalone server). This also helps with point #2, as the internal IPs stay static through restarts/stops.

Best Answer

Related Solutions

AWS VPC Multiple IPs

Elastic IP vs EC2 Public Hostname + Route53

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